Self-assembly of inorganic nanoparticles into ordered structures (superlattices) has led to a wide range of nanomaterials with unique optical, electronic, and catalytic properties. Various interactions have been employed to direct the crystallization of NPs, including van der Waals forces, hydrogen bonding, as well as electric and magnetic dipolar interactions. Among them, Coulombic interactions have remained largely unexplored, owing to the rapid charge exchange between nanoparticles bearing high densities of opposite charges (superionic nanoparticles). In this talk, I will describe a new method to assemble superionic nanoparticles under conditions that preserve their native surface charge density. Our methodology was used to assemble oppositely charged NPs into high-quality superlattices exhibiting Catalan shapes. This methodology can be applied to a wide range of charged nanoparticles of various sizes, shapes, and compositions. I will also discuss two ways to employ electrostatic interactions to assemble nanoparticles into transient assemblies, whose lifetimes depend on and can be controlled by the availability of a small-molecule ionic “fuel”.
Rafal Klajn completed his undergraduate education and an MSc in Chemistry at the University of Warsaw in 2004. In 2009 he obtained a PhD degree in Chemical & Biological Engineering at Northwestern University. He then joined the Weizmann Institute of Science, where he is currently a full professor. He has served on the boards of several journals, including Chem and ACS Nano, and received several awards, including the Netherlands Scholar Award for Supramolecular Chemistry, the Cram Lehn Pedersen Prize in Supramolecular Chemistry, and the Sigma-Aldrich lectureship in Materials Science.